Its not an April Fools joke, I read an article on it a few days ago, I'll try to find a link to prove the publish date. But it didn't specifically state DLC. Someone from Bethesda just had a twitter comment up saying "Big news for Skyrim and Rage fans coming in April". While this probably means DLC, I'm preparing myself for it to be something else, just in the case that its not and I get disappointed lol